1. Field of the Invention
This invention relates generally to a refrigerant piping system for a refrigeration apparatus or equipment such as, for example, an ice making machine, refrigerator or the like which is provided with a compressor, a condenser, etc. More particularly, this invention is directed to a refrigerant piping system including an injection pipe which is connected to the discharge port of the condenser and the suction (intake) port of the compressor to supply a coolant or refrigerant to the compressor.
2. Description of the Prior Art
FIGS. 3 to 6 of the accompanying drawings show an example of a conventional automated ice making machine. Referring to FIGS. 4 and 5, a reference numeral 1 denotes generally a vertically mounted ice making plate comprising a stainless steel plate. The ice making plate 1 has a rear surface 1a provided with an evaporator 2 constituted by a meandering tube and installed thereon in a heat exchange relation. Formed integrally with the ice making plate 1 are a plurality of protrusions 3 which extend in the vertical direction in parallel with one another with a predetermined distance therebetween in the transverse or horizontal direction so that the ice making plate 1 presents as a whole a configuration like a corrugated plate. Thus, there are defined on the front surface 1b of the ice making plate 1 between the adjacent protrusions 3 a plurality of ice making surface areas or divisions 4 at locations corresponding, respectively, to the horizontally extending sections of the meandering tube constituting the evaporator 2. These surface areas 4 are destined to form thereon ice pellets 5 each of a semi-cylindrical form during an ice forming cycle.
Disposed above the ice making plate 1 is a deicing water distributing pipe 6 which is connected to a deicing water supply pipe (not shown) and which has a plurality of water distributing orifices 6a formed therein for supplying deicing water over the rear surface 1a of the ice making plate 1.
Next, referring to FIG. 3 which shows a refrigerant piping system incorporated in the ice making machine having the ice making plate assembly 1 as described above, the evaporator 2 constituted by the meandering tube is fluidly communicated at a lower end 2a thereof with a suction (intake) port of a compressor 8 through a first conduit 7. The compressor 8 has a discharge port which in turn is communicated with an inlet port of the condenser 10 through a second conduit 9. Further, the condenser 10 has an outlet port connected to an expansion valve 12 by way of a third conduit 11 which valve in turn is connected to the evaporator 2 at the upper end 2b thereof through a fourth conduit 13. Mounted at the lower end portion 2a of the evaporator 2 is a temperature sensor 12b for the expansion valve 12, which sensor is connected to the latter through a capillary tube 12a.
Connected between the second conduit 9 and the fourth conduit 13 at respective branching portions 9a and 13a is a hot gas pipe 14 in which a hot gas valve 15 is mounted. Further, an injection pipe 30 which interconnects the third conduit 11 and the first conduit 7 at respective branching portions 11a and 7a has incorporated therein a capillary tube 28.
FIG. 6 shows a control circuit 19 for controlling the icing/deicing operation cycles of the ice making machine equipped with the refrigerant piping arrangement described above. As will be seen in FIG. 6, the control circuit 19 includes an electronic controller 20 having a relay 21 which is provided with a normally closed contact X1 and a normally open contact X2. Connected to the electronic controller 20 are a water level responsive switch 22 for detecting completion of the icing operation cycle (i.e. ice making operation cycle) which switch is mounted within a raw water storage tank (not shown) for containing raw water to be supplied to the ice making plate assembly 1 and a temperature responsive switch 23 which is mounted on the ice making plate 1 for detecting completion of the deicing operation cycle (i.e. ice removing cycle). Connected to the normally closed contact X1 of the relay 21 are a pump motor 24 for driving a pump for circulating the raw water from the tank through the ice making plate assembly, and a fan motor 25 for cooling the condenser. On the other hand, there are connected to the normally open contact X2 the hot gas valve 15 constituting a part of the deicing circuit 27 and a feed water valve 26 for supplying the deicing water.
Now, description will be made of the operation of a prior art ice making machine of the structure described above. Upon power-on, the pump motor 24 is energized to supply the raw water to the ice making surface areas 4 of the ice making plate 1 from the raw water tank through a water distributing tube (not shown). At the same time, the fan motor 25 is rotated to cool the condenser 10 with the compressor 8 being concurrently actuated. Thus, the coolant condensed by the condenser 10 is forced to pass through the expansion valve 12 and the evaporator 2. In the course of passing through the evaporator 2, the coolant is vaporized by absorbing latent heat from the raw water flowing downwardly along the ice making plate, whereby the raw water is frozen to form the ice pellets 5 on the icing surface areas 4. A part of the liquid coolant resulting from condensation by the condenser 10 is fed back to the compressor 8 through the capillary tube 28 to cool the compressor 8 for the purpose of preventing the temperatures of the individual parts constituting the compressor 8 from rising excessively.
When the ice pellets 5 have grown to a predetermined size, the water level switch 22 detects a lowering of the water level within the unshown raw water tank to thereby energize the relay 21 in the electronic controller 20. As a result, the normally closed contact X1 is turned off (opened) while the normally open contact X2 is turned on (closed), stopping operation of the pump motor 24 and the fan motor 25. On the other hand, the feed water valve 26 and the hot gas valve 15 are energized to be opened to supply hot gas to the evaporator 2. At the same time, deicing water is distributed over the rear surface 1a of the ice making plate 1 from the deicing water distributing pipe 6 to start the deicing (or ice removing) operation cycle.
When all the ice pellets drop off from the ice making plate 1 in the deicing operation cycle, the temperature sensor switch 23 provided in association with the ice making plate 1 detects a corresponding temperature rise of the ice making plate to thereby terminate the deicing operation cycle.
As will be understood from the above description, in the case of the prior art refrigerant piping system, the hot gas valve 15 is opened during the deicing operation cycle to allow the high temperature gas discharged from the compressor 8 to flow through the evaporator 2, whereby a portion of each ice pellet 5 (the portion contacting the ice making plate) melts under the influence of heat carried by the hot gas to thereby cause the ice pellets to be detached and removed from the ice making plate. In the course of this process, the gas is condensed in the evaporator 2 to be transformed into a liquid coolant which then flows into the compressor 8. At that time, liquid coolant is additionally supplied from the injection pipe 30 having the capillary tube 28 to flow into the compressor 8. As a result, a large amount of the liquid coolant flows into the compressor 8 to cool the latter excessively, giving rise to problems in respect to the stable operation of the compressor 8.